Corrosion inhibitor binding in an acidic medium: Interaction of 2-mercaptobenizmidazole with carbon-steel in hydrochloric acid

Mechanistic understanding of the functionality of organic corrosion inhibitors in acidic media is essential to knowledge-based performance optimization. In this study, we address a key issue hindering progress in this area, namely the chemical nature of the corrosion inhibitor/substrate interface. X-ray photoelectron spectroscopy (XPS) is employed to reveal the surface termination of carbon-steel, following immersion in 1 M hydrochloric acid inhibited with 2-mercaptobenzimidazole (MBI). Core level spectra indicate that the termination varies as a function of MBI concentration, with the interface consisting of MBI bound to film-free carbon-steel on highly inhibited substrates.